Syntheses, structural diversity, and selective luminescence sensing of three Co(II)/Cd(II) metal–organic frameworks composed of carboxylic acids and nitrogen‐rich mixed ligands

By adopting mixed‐ligand strategy, three Co(II)/Cd(II) metal–organic frameworks were prepared by hydrothermal reactions of Co(II)/Cd(II) acetate with 1,2‐phenylenediacetic acid or 1,3‐phenylenediacetic acid(1,2‐H2phda/1,3‐H2phda) combining with two imidazolyl/trazol/pyridyl‐type tectons, namely, {[Co(1,2‐phda)(bip)(H2O)2]·0.25H2O}n (1), {[Cd0.5(1,2‐phda)0.5(bip)0.5(H2O)0.5]·0.5H2O}n (2) and [Cd2(1,3‐phda)2(itmb)2]n (3) (bip = 3,5‐bis(1‐imidazoly)pyridine and itmb = 1‐(imidazo‐1‐ly)‐4‐(1,2,4‐trazol‐1‐ylmethyl)benzene). The single‐crystal X‐ray diffraction analyses show that three compounds contain various metal(II)‐carboxylate motifs, including carboxylate mononuclear (1), carboxylate chain (2), and carboxylate layer (3), which are further extended by two kinds of coligands to afford a vast diversity of the structures from 3‐connected {63}‐hcb topology (1), (4,4) grids layer (2) to 6‐connected {412·63} pcu topology (3). Furthermore, the photoluminescences of both Cd(II) complexes exhibit highly selective sensing of Fe3+ ion through fluorescence quenching, and may be used as a potential Fe3+ sensor material. Three Co(II)/Cd(II) metal–organic frameworks (MOFs) based on flexible phenylenediacetic acid and nitrogen‐rich coligand have been synthesized and characterized. Their structure show a varieties of structures from 3‐connected {63}‐hcb topology, (4,4) grids layer to 6‐connected {412·63} pcu topology. Furthermore, the photoluminescences of both Cd(II) complexes exhibit highly selective sensing of Fe3+ ion through fluorescence quenching, and may be used as a potential Fe3+ sensor material.